A. Field of the Invention
The present invention relates to a data network and, more particularly, to a data network that facilitates bidirectional wireless data communications between a microcomputer unit and a plurality of peripheral units located within the proximity of the microcomputer unit.
B. Description of Related Art
The size and power consumption of digital electronic devices has been progressively reduced so that personal computers have evolved from lap tops and notebooks into hand-held or belt-carriable devices commonly referred to as personal digital assistants (PDAs). One area of carriable devices that has remained troublesome, however, is the coupling of peripheral devices or accessories to the main processing unit of the PDA. With rare exceptions, such coupling has typically been provided by connecting cables. The connecting cables restrict the handling of the PDA in such a manner as to lose many of the advantages inherent in the PDA""s small size and light weight.
While some conventional systems have proposed linking a keyboard or a mouse to a main processing unit using infrared or radio frequency (RF) communications, such systems have typically been limited to a single peripheral unit with a dedicated channel of low capacity.
Based on the foregoing, it is desirable to develop a data network of low power consumption that provides highly reliable bidirectional data communication between a host or server microcomputer unit and a plurality of peripheral units while avoiding interference from nearby similar systems.
Systems and methods consistent with the principles of the present invention address this need by providing a wireless personal area network that operates at low power and permits a host unit to communicate with peripheral units with minimal interference from neighboring systems.
A communications protocol consistent with the present invention is used in a network having a hub device connected to a plurality of peripheral devices. The communications protocol includes a synchronization beacon frame that is broadcast by the hub device to the peripheral devices for permitting the peripheral devices to synchronize to the network, a token frame that is broadcast by the hub device to the peripheral devices for allocating network bandwidth among the peripheral devices, a status response frame that is transmitted by the peripheral devices to the hub device for indicating whether the peripheral devices have data to transmit to the hub device, and a data frame.
The synchronization beacon frame includes a beacon identifier that identifies a frame as the synchronization beacon frame, and a hub identifier that identifies an address of the hub device. The token frame includes a data portion that schedules a data transmission on the network, and a status response portion that schedules a status response transmission on the network. The status response frame includes a data transmission field that indicates whether a corresponding one of the peripheral devices has data to transmit to the hub device. The data frame includes data transmitted between the hub device and the peripheral devices.